Research Of Lensless Holography Microscopy System And Reconstruction Algorithm

Optical microscope has been the main tool of biomedical imaging for centuries.Its performance depends on the relatively cumbersome,complex and expensive lens and other optical mechanical components.The traditional high-resolution optical microscope relies on high-power and high numerical aperture objective lens for imaging.At the same time,there is a trade-off relationship between the resolution and the field of view due to the inherent mechanism.When the imaging resolution is higher,the field of view is smaller.In contrast,lensless microscope can achieve high-resolution imaging without using any focusing lens,and it can significantly surpass the limited space bandwidth product of the traditional microscope objective lens to achieve large field of view high-resolution microscopic imaging.In this paper,through theoretical analysis,simulation calculation and experimental verification,the imaging principle,imaging resolution analysis and optical wavefront reconstruction algorithm of in-line holography on-chip microscopy are systematically studied.The main research contents include:1.The scalar diffraction theory and three standard direct reconstruction methods are discussed for in-line holography.The principle and conditions of recording and reconstruction of digital holography are discussed.The factors influencing the resolution of in-line lensless holography are analyzed.2.The algorithm of axial difference auto focusing is proposed,and the comparison of several common image quality evaluation operators proves that the proposed algorithm has higher focusing accuracy.The algorithm of sub-pixel alignment using up sampling Fourier transform matrix is discussed and analyzed.3.We propose a Gaussian noise robust Wirtinger Flow(WF)gradient descent algorithm for wavefront reconstruction,and discuss other phase retrieval algorithm including Gerchberg-Saxton and its derivative algorithm.The results of simulation and experiment show that the algorithm is effective.The system with a large field-of-view(FOV)of about 30mm~2 and a resolution of about 1.6μm is achieved.